How severe is CVE-2020-18702?

CVE-2020-18702 has a CVSS score of 6.1/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2020-18702?

CVE-2020-18702 affects the following packages: quokka (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2020-18702?

No patched version of quokka has shipped for CVE-2020-18702 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.

How do I detect CVE-2020-18702 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for quokka, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2020-18702 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is CVE-2020-18702 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2020-18702, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2020-18702?

CVE-2020-18702 has an EPSS (Exploit Prediction Scoring System) score of 1.3%, placing it in the 70th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2020-18702?

CVE-2020-18702 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2020-18702 published, and has it been updated?

CVE-2020-18702 was published on August 16, 2021 and was last updated on July 8, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍

🐍 PyPI

Not in CISA KEV

MEDIUM severity

CVE-2020-18702 — quokka

MEDIUM

CVE-2020-18702 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in quokka. 1 public exploit reference exists, so weaponization risk is real. No vendor fix is recorded yet; mitigation options are listed below.

Cross Site Scripting (XSS) in Quokka

Also known asGHSA-5m69-3chg-6f8mPYSEC-2021-143

Published

Aug 16, 2021

Updated

Jul 8, 2026

Affected

1 pkg

Patched

See advisory

Exploits

1 known

Exploitation data as of Oct 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs70th percentile — riskier than 70% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2020-18702 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,386 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

🐍quokka

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

Cross Site Scripting (XSS) in Quokka v0.4.0 allows remote attackers to execute arbitrary code via the 'Username' parameter in the component 'quokka/admin/actions.py'.

Affected Packages

1 total

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`quokka`	all versions	No fix

Affected Products

1 product · 1 configurations

Application

quokkaquokka_project

1 version

0.4.0

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Cross Site Scripting (XSS) in Quokka v0.4.0 allows remote attackers to e…

github.comNVDAug 2021

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for quokka, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
No patched version of quokka has shipped for CVE-2020-18702 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

Cross Site Scripting (XSS) in Quokka v0.4.0 allows remote attackers to execute arbitrary code via the 'Username' parameter in the component 'quokka/admin/actions.py'.

O3 Security · Impact-Aware SCA

Is CVE-2020-18702 in your dependencies?

Find it across PyPI, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

6.1/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Raw vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CWE Classification

CWE-79Cross-site Scripting (XSS)

Weaponization

No known public exploit tooling found.

OpenSSF Scorecard

Package health score

quokka

1.9/10

Code-Review2/10

Maintained0/10

Branch-Protection0/10

Assessed Oct 5, 2026

Timeline

Disclosed

Aug 16, 2021

First exploit

Aug 23, 2021

7 days after disclosure — rapid exploitation

Last updated

Jul 8, 2026

Identifiers

CVE-2020-18702

GHSA-5m69-3chg-6f8m

PYSEC-2021-143

References

Advisorynvd.nist.gov Advisorygithub.com Fixgithub.com Webgithub.com Packagegithub.com

Related vulnerabilities

Also affects quokka

This CVE is medium severity; 2 of 2 other CVEs affecting quokka are rated as high or higher (top: critical).

CVE-2020-18703CVE-2020-18705

Same weakness: CWE-79

This CVE is medium severity; 6 of 6 other CVEs with CWE-79 are rated as high or higher (top: high).

CVE-2026-91127CVE-2026-77606CVE-2026-84992CVE-2026-77608CVE-2026-77607GHSA-9rcc-pmj8-ffhrBrowse all CWE-79

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedJul 8, 2026